A Novel Point Mutation (L837F) in Osmosensor-like Histidine Kinase FgOs1 Drives Potent Fludioxonil Resistance in .

is a preeminent fungal pathogen exacting a heavy toll on global crop production. Fludioxonil, a highly effective broad-spectrum fungicide, has been extensively deployed to mitigate the devastation wrought by Nevertheless, the molecular mechanisms of fludioxonil resistance in this pathogen remain largely enigmatic. In this study, we identify a novel point mutation (L837F) in FgOs1 (osmosensor-like histidine kinase), which is located in the HIS_KIN (histidine kinase) domain. Biological assays revealed that the FgOs1 mutation reduced the ability of . to adapt to low-temperature stress, osmotic stress, and metal ion stress and also decreased its pathogenicity. Additionally, this mutation did not confer cross-resistance to the fungicides phenamacril, tebuconazole, and carbendazim. To facilitate field monitoring, we employed allele-specific PCR (AS-PCR) to detect FgOs1 point mutation in . . This study offers crucial support for fungal disease control and crop protection.